Climate Migration – an Introduction

Climate Advisory

It is already occurring.

A decade ago, climate migration may have seemed like a longer-term prospect and/or something that wouldn’t be widely applicable to the US for many years.  The unfortunate events since that time, including an increase in frequency and intensity of coastal and inland flooding, the ever-intensifying challenge of drought and wildfires, rapidly thawing permafrost and oppressive heat waves have made this the emerging challenge of our times.  

In the US alone, we are witnessing several of these movements already.  Two examples include the relocation of the Yupik from the shores of the Ninglick River in Newtok, Alaska and the Biloxi-Chimacha-Choctaw tribe from the Isle de Jean Charles in Louisiana.  Other relocations are also occurring but in a less obvious way – these include individual decisions not to resettle or rebuild in areas impacted by floods, fire or drought and permanently relocating to areas which seem more resilient.  From a corporate perspective, asset owners and managers are starting to incorporate climate risk considerations into investment decisions – assessing the perceived resilience of a particular geography, the potential for un-insurability or devaluation issues in the future, etc. These types of movements are more nuanced and difficult to track but, cumulatively, will also result in noticeable demographic shifts in the near future.

What can past settlement patterns teach us about future ones?

Interestingly, when looking back through the last 6,000 years of settlement data, researchers have discovered that humans have occupied a relatively narrow climatic band.  The main driver in establishing this “human ecological niche” seems to be tied to temperature.  With an increase in global temperatures, it is anticipated that the current expanse of that niche will become further constricted.  In as little as 50 years, it is anticipated that 1 to 3 billion people will be located outside of that preferred niche.  The implications of such a shift are sobering. What does sustainable development look like in that scenario? 

Projected shift of the human ecological niche as a result of climate change.
Source: PNAS (Figure 4)

  The projected shift shown on Map B is calculated using RCP 8.5 projection data.  Map C represents the differences between Maps B and A, highlighting areas of anticipated out-migration (oranges and reds) and in-migration/receiving areas (greens).

ProPublica recently released an insightful but equally sobering article on climate migration. As part of that work, they shared a mapping project that tracked how the areas of “suitable habitat” could change under varying climates.  The work took into account a number of factors including different emission scenarios, as well as changes in temperature, moisture, drought, wildfire vulnerability and arable lands.

According to their study, with the next 50 years, the area available for large-scale food production in the US will undergone a major northward and inland retreat (under both the low emissions and high emission scenarios). The same changes that will lead to this shift in arable land, will also impact where people are likely to live. 

Shift in “suitable habitats” (indicated by greens) by 2070 under the low emission (RCP 4.5 scenario).  

Shift in “suitable habitat” (greens) by 2070 under a high emission (RCP 8.5) scenario.

It is an interesting exercise to compare those projections to the existing demographics of the U.S. What sorts of policies and other planning strategies would need to be implemented to ensure a smooth, equitable and sustainable transition to such a different set of boundary conditions?  And in such a relatively short period of time?


Translating large-scale trends into more localized considerations

There is an urgent need to translate these macro-level trends into more site-specific projections so that states and municipalities can proactively plan for change. The field of climate migration is still evolving but early work provides interesting insights into potential behaviors, biases and pathways.  Below are two examples.

Sea-level rise and Climate Migration

One of the earlier and more influential papers to come out on this subject focused on the relationship between sea level rise and future demographic shifts within the US (Climate change migration induced by sea-level rise could reshape population landscape).  The research focuses on sea-level rise as the main driver and assumed no additional adaptation measures.  It provides interesting insights into possible futures based on where people might relocate in order to escape the impacts of increased coastal flooding.  Many of those relocations involved simply moving elsewhere in the state, while others are expected to involve interstate travel.

Graphics showing net migration (in-migrants minus out-migrants) for counties (a) and core-based statistical areas (b). 

Top ten outflow states under a six foot sea level rise scenario: Florida, Texas, New York, California, Louisiana, New Jersey, North Carolina, Georgia, Massachusetts, South Carolina, Virgina.  For more details, view this article.

Economic winners and losers

As climate change redefines the location and extent of our “suitable habitats” it will also introduce significant social and economic disruptions.  A recent research collaboration undertook an extensive analysis across a variety of drivers to get a better understanding of how those economic damages might present, and how that information could be leveraged to inform future policies.  Both market and non-market damage indicators were used including a focus on agriculture, energy, labor, and human mortality and including disruptors such as crime and coastal storms.   Key findings included the fact that the risk and damages were unequally distributed across geographies and populations, that some northern areas could actually experience positive opportunities related to climate change, and that a large portion of the middle and lower US would likely experience mostly negative impacts.  The map below is a summary compilation of those results; however, the peer-reviewed paper and supporting analyses are deserving of further reading, as there are other interesting findings across individual indicators as well.   

At the heart of both of these pieces of work are the larger policy and governance implications associated with such a rapid and transformational shift.  Who will take the lead on developing these policies? How will these policies be coordinated across federal, state and local levels?  Will traditional property right laws and land use regulations have to be rewritten?  Within existing property right laws, there is usually the unstated assumption that a piece of land will continue to maintain the same environmental characteristics that it had when it was originally purchased (barring any direct human intervention).  What happens when that is no longer the case?  What happens when a large number of people start to experience a change in land use based on climate impacts (e.g., flooding, wildfire, drought, erosion, etc.)? Currently, insurance coverage is mainly underwritten to protect the value of built structures.  How might that change if environmental aspects, ecological services and other types of natural capital start to become valued and monetized (similar to the carbon market)?  

The looming issue of climate migration has forced us to start to think differently about land use.  The predictability of how a parcel land will function is no longer guaranteed in a changing climate. The continued increase in climate disruptions will be a accompanied by a change in overall land valuation criteria. People will likely look to move to areas that they feel have greater resilience.  While the trends may be national, the solutions (resettlement or inability to move) will be implemented at a local level.  It will therefore require a coordinated effort across the federal-state-local jurisdictions. 

Future Blogs

Climate migration has gained more recognition and acceptance as a likely near-term impact of climate change.  Property rights issues, land valuation and valuation of nature-based processes and ecosystem services are closely tied to this topic. Many of these areas will be the subject of future blogs and will include both public sector and investor-based perspectives, an examination of market drivers, as well as the financial and economic considerations associated with these large-scale demographic shifts.  What does sustainable development look like in the midst of a narrowing ecological niche?

Get in Touch

If your project is a good fit, we’ll reach out to schedule a complimentary discovery call for next steps.